[Declanomous]

Pupillary distance is basically the horizontal location of the pupils. The issue is that pupils can also have a vertical offset from the center of the lens as well. Accounting for PD alone is sufficient for some people. I'm not a doctor, so I'm not qualified to recommend one option over another. It is something you may want to ask your own doctor about though.

[dubyah]

To be fair to Zenni, most online eyeglass sites don't request vertical measurements as the PD is sufficient for the majority of single vision users and there isn't a single vertical measurement that can be applied from one user to other glasses. Ocular center height is very subjective & measured during the fitment of that frame to the user. Optical center being the same height as geometric center is a safe choice for something only made to measure.

There are sites that take segment height for bifocals, but the intended frames need to be in hand for the user to measure.

[rhizome]

Are there any magic words to account for this that I/we can use when getting a new prescription?